Much fishing is done from the stern or rear end of a slowly moving boat, a procedure known as trolling. One drawback to fishing using this procedure is that the forward motion of the boat tends to straighten and raise the fishing line and its attached bait or lure, the result being that only fish near the surface of the water are attracted to the lure. Since many fish do not venture near the water's surface, due to factors such as the additional warmth of the water temperature, habitat, increased light intensity, and others, catching deep-water fish has been possible only from a stationary boat or pier. The success of the trolling procedure, however, stems from the attractiveness to fish of a moving lure. These problems have been alleviated by the use of devices known as downriggers. A downrigger is a device that allows one to fish at a certain selected depth while trolling. The hook is attached and baited, or a lure is attached to a primary fishing line emanating from a rod and reel assembly, and is then let out behind the boat a certain desired distance. The fishing line is then releasably fastened to a heavy or weighted ball which is lowered the desired distance into the water. The ball normally weighs approximately ten pounds and is fastened to a steel cable which can be as much as six hundred feet in length. The ball remains at approximately the depth selected and drags the lure along behind the boat at the depth of the ball.
When a fish strikes the lure, the fishing line is released from the ball and the fisherman takes control to land the fish. The ball is returned to the downrigger assembly, automatically or by reeling in the cable by hand, ready for the next attempt. This allows some selection over what species of fish is caught, since it is generally known by experienced fishermen, or local conservation officers, at what approximate depth certain species of fish swim. The downrigger also allows fishing along the bottom or a few feet from the bottom in bodies of water having known depths, and one can select with reasonable accuracy the fishing depth and the species of fish desired.
Most fishermen endeavor to increase their catch, or at least their chances of catching fish, and one procedure followed is the attachment of multiple lines and hooks or lures to the primary fishing line. The rationale varies, but, in general, it is believed that multiple lures are better than one, and multiple baits give to the targeted species the impression of a school of possible food, thereby increasing the attractiveness to the fish. Most states, however, have codes applicable to fishing in inland waters within or adjacent their boundaries and limit the number of lines, or the number of hooks or lures, which may be attached to each primary line emanating from a single rod. Michigan, for example, generally limits each person to no more than two lines and no more than four hooks on all lines. Indiana, as another example, generally limits each person to no more than three lines, and no more than two hooks or lures per line. Thus, many devices and methods have been tried for attaching additional leaders or lines to a primary line. Some of the aforementioned devices or methods include swivel snaps, alligator clips, rubber bands, or simple knots for tying an auxiliary line to a primary line. In some cases, auxiliary lines have even been hooked to the downrigger cable, but the results have been less than satisfactory with any of the above devices or methods. Where two or more lines are used with a single rod, the inability to control the separation of the lines usually results in tangled lines, broken lines, escaped fish, or fish that must be pulled in by hand where the primary line can not be reeled in due to the engagement of the swivel snap, knot, or alligator clip with the eye or guide member at the tip of the fishing rod.